Assuming that a) using the email to request the new password isn’t an option AND b) you have access to mysql or phpMyAdmin you may use the following methods to recover the password for your drupal root user:

drupal 6:

In drupal 6 the password is stored as a simple MD5 hash of your plain […]

—————————————————————— You are maintaining several web-sites (site1.com, site2.org, etc…). Having just one web-site at localhost with all files (DocumentRoot) at /var/www/html is not an option for you. You need to be able to test all of them and to access them in a convenient way.